angeles and in other places, if you take a child in the third grade at the middle level in the 50th percentile, math and reading, and give him an excellent teacher, in two years that child will be at the 80th percentile, if you give that child a poor teacher, that child in two years will be at the 20th percentile. what more do we need to know? but that good teachers make a huge difference in the life of a child. not all the difference. not everything. most important person in the child's life is a parent, obviously. but if you can move from the 50th to the 80th with a teacher or 50 to 20 with a poor teacher you've got to pay attention to the quality of the teaching force. the true evaluation isn't just about improving teachers. it's also about identifying who are the ones who should be promoted, rewarded, given more opportunity, given more responsibility, and encouraging out 69 profession people who are -- out of the profession people who are harming kids. host: how do you do that fairly? guest: you do it fairly through a number of monies and people with be -- can be open minded abo